Design Strategy Paving Way to Multi-Electrode Deep-Brain Stimulation

Published on April 21, 2009 at 6:07 AM

At this week's Design, Automation + Test in Europe (DATE) conference, IMEC
presents a new design strategy for brain implants, which it used to create a
prototype multi-electrode stimulation + recording probe for deep-brain stimulation.
With this development, IMEC highlights the opportunities in the healthcare market
for design tool developers.

Brain implants for electrical stimulation of specific brain areas are used
as a last-resort therapy for brain disorders such as Parkinson's disease, tremor,
or obsessive-compulsive disorder. Today’s deep-brain stimulation probes
use millimeter-size electrodes. These stimulate, in a highly unfocused way,
a large area of the brain and have significant unwanted side effects.

Wolfgang Eberle, Senior Scientist and project manager at IMEC’s bioelectronics
research group: “To have a more precise stimulation and recording, we
need electrodes that are as small as individual brain cells (neurons). Such
small electrodes can be made with semiconductor process technology, appropriate
design tools, and advanced electronic signal processing. At DATE, we want to
bring this message to the design community, showing the huge opportunities that
the healthcare sector offers.”

The design strategy relies on finite-element modeling of the electrical field
distribution around the brain probe. This was done with the multi-physics simulation
software COMSOL 3.4 and 3.5. The COMSOL tools also enabled investigating the
mechanical properties of the probe during surgical insertion and the effects
of temperature. The results indicate that adapting the penetration depth and
field asymmetry allow steering the electrical field around the probe. This results
in high-precision stimulation. Also key to the design approach is developing
a mixed-signal compensation scheme enabling multi-electrode probes capable of
stimulation as well as recording. This is needed to realize closed-loop systems.

These new design approaches open up possibilities for more effective stimulation
with less side effects, reduced energy consumption due to focusing the stimulation
current on the desired brain target, and closed-loop control adapting the stimulation
based on the recorded effect.